The present invention relates to minimally invasive surgical instruments for the incision and removable of a wide range of tissues. Specifically, the invention concerns disposable surgical cutting assemblies for operative engagement with powered hand-pieces.
Many medical treatments involve the removal of body tissues. In recent years, it has become standard to employ automated systems and less invasive surgical methods in order to achieve the best surgical outcome. Automated systems improve efficiency and effectiveness, particularly when the procedure requires cutting and removal of fibrous tissues that are difficult to completely sever. Minimally invasive surgical techniques avoid the trauma and expense of traditional surgical approaches because the site of pathology is accessed through portals rather than through a significant incision, thus preserving the integrity of intervening tissues. In some cases, these minimally invasive techniques require only local anesthesia, reducing post-operative recovery time and the risk of complications.
These recent improvements are particularly beneficial in the intricate, micro-surgical fields such as surgical ophthalmology and neurosurgery where extreme precision is essential, yet many of the tissues encountered can be fibrous. In these fields, surgical cutting probes are used to separate and remove pathologies from delicate structures. Fine discrimination and manipulation is required to avoid damaging healthy tissue. For example, certain conditions require the removal of tissue, such as vitreous, from the eye to preserve vision or maintain eye health. Removal of the vitreous is difficult due to the presence of fibers and the risk of serious complications, such as detachment of the inflexible, yet delicate, retina.
Since some of the fibers contained within the vitreous are attached to the retina, any incomplete cutting of the fibers could create retinal traction which could lead to retinal detachment. Incomplete cutting may result from a dull cutting blade, wherein the blade would merely pull the fibers and increase the retinal traction, or from a poor interface of the cutting edges of the outer needle and the cutting blade wherein the shearing effect of the edges passing across one another is reduced. In addition, imperfect alignment of the cutting blade within the outer tube could cause the shearing action to be localized at the center of the cutting edges and prevent the outer portion of the cutting edges from interfacing sufficiently close enough for a clean shearing action to occur.
Many of the known surgical tissue cutting instruments, for ophthalmology and other applications, employ the xe2x80x9ctube within a tubexe2x80x9d technology. These devices combine constant suction with a repeated cutting motion of a blade. Typically, an inner cutting sleeve is operated within the central bore of an outer cutting sleeve. The outer sleeve defines one or more apertures for receiving tissue when suction is applied. The inner sleeve can be reciprocated or rotated within the outer sleeve to pass a cutting edge past the aperture to cut tissue.
Although such automated cutters are a mayor advance in the art, several problems have been identified, such as incomplete cutting, clogging and the inability to cut harder tissues. Some of these problems arise from dull cutting blades or imperfect alignment of the blade within the outer tube. Over the years, many improvements to the basic tube within a tube design have been developed in an attempt to address these functional problems. While it has been a formidable challenge to address these problems while maintaining the minimally invasive features of the devices, some have been successful. An example of such an improvement is disclosed in U.S. Pat. No. 5,782,849 issued to Miller.
In addition to these functional issues, the risk of the transmission of infective agents must also be addressed. Disposable devices and/or sterilization procedures are employed. For example, disposable blades can be coupled with reusable, sterilizable hand-pieces. In some commercially available systems, the disposable surgical blades are connectable to a hand-piece through a locking collar, spring, and key and groove arrangement. Unfortunately, these arrangements are complicated and cumbersome, increasing the fiddle factor and risk of malfunction. Moreover, the locking collars and other components can become contaminated with tissue, preventing proper function of the connection mechanism.
Therefore, one problem that has remained unsatisfied in the art is the need for disposable surgical cutter components that provide convenient reasonable cost. Accordingly a need has remained for disposable surgical cutting components that can be easily and efficiently assembled and yet provide precision operation.
Briefly describing certain aspects of the invention, a surgical cutting instrument is disclosed. The instrument includes a hollow hub having a working portion, which terminates at a working end and a connection portion, which terminates at a connection end. The connection portion defines a cavity and a lock member which projects from an outer surface of the connection portion. An outer tubular member extends from the working end and is sized for insertion into an anatomical space. The outer tubular member defines a central bore along the length I of the outer tubular member. The outer tubular member has a proximal end attached to the working end of the hub and a distal end. The outer tubular member further defines a cutting opening adjacent the distal end and sized to receive tissue therethrough.
A cutting member is slidably disposed within the central bore of the outer tubular member. The cutting member has a first operational end, which defines a cutting head, and a second engagement end disposed within the cavity of the hub. A drive element is also disposed within the cavity and has a drive mount portion connected to the engagement end of the cutting member. The drive element further has a mating portion operationally connectable to a source of motion. The drive element translates motion from the source of motion to the cutting member to move the cutting member relative to the outer tubular member so the cutting head traverses the cutting opening. The instrument includes a powered hand-piece having a source of motion and an outer shell, which defines an outer gripping portion.
A hollow hub connector is provided within the handpiece. The connector has a cylindrical wall with a hand-piece connection portion and a hub engagement portion. The connection portion is disposed within and is connected to the hand-piece. The hub engagement portion defines a chamber for receiving the connection portion of the hub. The chamber has a longitudinal axis AL parallel to the length of the hub connector. The hub engagement portion further defines a channel through the cylindrical wall for receiving the lock member. The channel is in communication with the chamber. The channel has a longitudinal section defined in the wall parallel to the length L of the connector. The channel also has a second transverse section communicating with the longitudinal section. A locking recess is defined in the wall perpendicularly to the transverse section, and in communication with the opposite end of the transverse section. The locking recess is sized to receive the lock member.
Thus, the connection portion of the hub is slidable within the chamber along the longitudinal axis when the lock member is disposed within the longitudinal section of the channel. The connection portion of the hub is rotatable within the chamber when the lock member is disposed within the transverse section of the channel. The connection portion of the hub is fixed within the chamber when the lock member is disposed within the locking recess.
In another embodiment, the invention includes a spring element disposed on the connection portion of the hub. The spring element urges the lock member into the locking recess wherein the locking member is rotated into the opposite end of the transverse section of the channel. The spring element has a squeezed position when the lock member is in the transverse section of the channel and a rest position when the lock member is in the locking recess. In preferred embodiments, the spring element is a beam spring disposed at the connection end of the hub. The beam spring includes a beam having a first face adjacent the connection end and a second opposite face with a boss projecting from the opposite face.
In still another aspect of the invention, the instrument includes a drive connector disposed within the chamber of the hub connector. The drive connector is operably engageable to the source of motion and releasably matable to the mating portion of the drive element when the hub is engaged to the hub connector. In some embodiments, the mating portion includes a transverse bar disposed within the cavity of the hub and the drive connector includes a bayonet element matable to the transverse bar. The bayonet element has a pair of spaced arms each terminating in a hook. The bayonet element is configured to releasably receive the transverse bar when the hub is disposed within the chamber and the lock members received within the longitudinal channel. When the hub is rotated the locking member is disposed within the locking recess, the transverse bar is captured by the hooks to thereby operatively engage the inner tubular member to the source of motion.
Accordingly, it is one object of the invention to provide disposable surgical cutter assemblies for operative engagement with powered hand-pieces. These and other objects, advantages and features are accomplished according to the devices and methods of the present invention.
FIG. 1 is a side perspective view of one embodiment of a cutter assembly according to this invention.
FIG. 2 is a partial sectional view of a surgical cutter including the hub assembly shown in FIG. 1.
FIG. 3 is a perspective view of a hub according to one embodiment of this invention.
FIG. 4 is a side sectional view of a cutter assembly of this invention.
FIG. 5 is a side sectional view of a cutter assembly of this invention.
FIG. 6 is a perspective view of one embodiment of a hub connector.
FIG. 7 is an exploded perspective view of a hub and connector assembly according to one embodiment of this invention.
FIG. 8 is a side perspective view of a cutter assembly of this invention with the locking member of the hub at the junction of the longitudinal and transverse sections of the channel of the hub connector.
FIG. 9 is a perspective view of a hub according to one embodiment of this invention.
FIG. 10 is a partial sectional exploded view of the cutter assembly shown in FIG. 1.
FIG. 11 is a side elevational view of a drive connector according to one embodiment of the present invention.